It is very often of importance to know the temperature of industrial processes to optimize the process, e.g. in relation to fuel consumption or process control.
Examples of systems for measuring a melt beam temperature are known from e.g. U.S. Pat. Nos. 4,297,893, 4,812,151 or EP 0 080 963. However, none of these more automated temperature measurement systems are suitable for measuring the elevated temperature of the molten raw material in mineral wool production.
However, also when producing mineral wool it is important to know the melt temperature. In mineral wool production raw materials are melted in a furnace and the melt flows through a siphon to a spinning device, such as a high speed wheel, to produce fibres.
The temperature of the melt is up to 1500° C., and the properties of the fibres produced are dependent on the precise temperature, and further the melt temperature has a significant impact on the fuel consumption and on the wear and tear of the equipment.
Temperature of the melt is however difficult to measure because of the very high temperature and adverse conditions.
Furthermore the temperature at the surface of the melt beam is considerably lower than the core temperature inside the melt beam, and ideally it is this melt beam core temperature, which should be measured.
Traditionally temperature measurement has been done manually by a person with either a contact thermometer, such as a thermo couple, measuring the core temperature of a melt beam, or a contactless thermometer of some kind, e.g. a pyrometer, which has an optical system and detector and measures thermal radiation from the melt beam, i.e. the surface temperature of the melt beam. Consequently, the measurements are subject to error. Moreover, such measurements are labour intensive to perform and hence costly.